Apparatus for casting hollow bodies



Aug- 27, 1940. J. NAGATSUKA APPARATUS FOR CASTING HOLLOW BODIES Filed Feb '7, 1939 2 Sheets-Sheet l INVENTOR. JD/vr/Ro Nae/#115 UKFI BY I v 1940- J. NAGATSUKA 2,212,844

APPARATUS FOR CASTING HOLLOW BODIES 7 Filed Feb. 7, 1939 2 Sheets-Sheet 2 I IN V EN TOR. JbMT/Ro NFIGYH TSu/rfl A TTORNE Y.

Patented Aug. 27, 1940 UNITED STATES APPARATUS FOR CASTING noLLow BODIES Junjiro Nagatsuka, Tokyo, Japan Application February I, 1939, Serial No. 255,033

2 Claims.

This invention relates to an apparatus for easting hollow bodies, the object of the invention being to provide an apparatus in which a metallic core is made use of and whereby the casting of cylinders of any size is accomplished more easily and quickly than heretofore.

Referring to the appended drawings which show diagrammatically an apparatus for carrying the invention into practice,

Figure 1 is a side elevation of the apparatus;

Figure 2, a front elevation;

Figure '3, a plan view, broken away;

Figure 4, a side view partly in section showing the interior construction of the essential part of this apparatus;

Figure 5, a section along the line V--V of Figure 4 and Figure 6, a section along the line VI-VI of Figure 4. A

In the drawings, l designates the vertical portion of a mould having a removable bottom 2 provided with a centrally disposed opening 3. in which is mounted for rotation a journal 5 formed at the end of a shaft 4, said journal being slightly smaller in diameter than the opening, as indicated in Fig. 4, whereby the journal will have a limited lateral movement or play in said opening. A core 4' is formedon the shaft 4 and is cut away at its periphery to form alongitudinally relieved portion Sat one side of the core, said portion being disposed in a line approximately parallel with the axis of the core, the radius of the core section being greater at said relieved portion than at any other portion of the core. The upper portion of the shaft 4 above the mould l is mounted in yielding bearings supported in brackets. 1, each of said bearings comprising a flexible ring l encircling the shaft, said ring being retained in position by springs 8 disposed in cruciform arrangement within a casing 9 formed as a part of the bracket 1. The mould I is secured by means of brackets to one of the uprights of a frame [4, the brackets I being also secured to ,said upright. Rotary motion is imparted to the shaft 4 by means of a belt and pulley transmission from a motor l6 mounted on the base of the frame l4, the motion-receiving pulley I I being secured on a horizontal shaft I! mounted for rotation at the top of the frame l4, said shaft carrying at its opposite end a bevel pinion IS in mesh with a similar pinion secured on the upper end .of the shaft 4.

For casting hollow bodies, metal cores are seldom used because of their liability to crack, and. in the rare instances in which they are used,

the core must be removed from the casting before cooling. Moreover, metal cores are impractical in the making of large castings, because all metals contract in cooling and are therefore subject to the so-called shrinking phenomenon.

Now, according to the present invention, as the core is made especially of a metal having a high melting point or is of air cooling or water cooling type, it may not only be used repeatedly many times even for large castings, but it provides the resulting casting with a hollow having a surface as smooth as if it had been planed;

In the present invention, the metal core is not subject to the shrinking phenomenon above referred to because of the action of the relieved portion 6 formed thereon. That is to say, when the core 4' rotates in a molten mass, the metal cools gradually and produces a hole at the center. This hole has a diameter twice as long as the largest radius of the core 4'. With the cooling of the casting, the core 4' is pressed by the inner wall of the casting at the part having the great- 1 est radius, in consequence of which there is a tendency to cause the so-called shrinking phenomenon, but as the center line of the bearing 1 which embraces the rotatable shaft 4 is shifted automatically, due to the flexibility of the bearing ring l0 and springs 8 the pressure above referred to is thus relieved, thereby avoiding injury to the shaft due to bending.

Instead of the longitudinally relieved portion 6, the core 4' may be formed like a column, in which case however the rotatable. shaft 4 and the journal 5 must be concentric, while the core 4' is eccentric to them.

The operation of the apparatus is very As shown in Figure 4, the core 4' is inserted into the vertical portion l of the mould, the journal 5 being borne by the hole 3 in the bottom and the shaft 4 slowly rotated, for instance, by the motor l6, pulley ll, driving shaft 12 and gearing l3. Next, a molten mass to be cast is poured into the mould as in the ordinary casting. When the molten mass is solidified, the opening therein will have a radius equivalent to the greatest radius of the core 4' and accordingly the inner wall of the casting will exert strong pressure upon the part of the core 4' equivalent to its greatest radius as it cools, so that the rotatable shaft will be inevitably moved laterally'of the mould, thus tending to bend the shaft. However, owing to the flexibility of the bearing Ill in any direction, the pressure on the shaft merely causes it to shift its position relative to the opening in the casting.

simple.

Upon removal of the bottom 2 of the mould, the casting will readily drop by gravity, whereupon the bottom is replaced and the apparatus is ready for the next operation.

In case of the product having a bottom, the vertical part i and bottom 2 of the mould may be formed integrally.

I claim:

1. A casting apparatus, comprising a metallic mold, a rotatable shaft mounted for rotation and lateral movement in said mold, and a metallic core carried by said shaft within the mold, said core having at its periphery a relieved portion extending parallel with the axis of the core whereby one portion of the cross-section of the core is of greater radius than all other portions thereof.

2. A casting apparatus comprising a metallic mold having a central opening in its bottom, a metallic core journaled at one end in said opening, the journal member being slightly smaller in diameter than said opening, and allaterally flexible bearing journaling the opposite end of the core whereby the latter is capable of lateral movement relative to the mold, said core having at its periphery a relieved portion extending parallel with the axis of the core whereby one portion of the cross-section of the core is of greater radius than all other portions thereof.

JUNJmo NAGATSUKA. 15 

